1. Field of the Invention
This invention relates to a transmitter for a radio control system which is adapted to remotely control each of controlled units including various kinds of models such as a model car, a model airplane and the like and a variety of industrial equipments such as a crane and the like, and more particularly to a transmitter for a radio control system exhibiting control characteristics which permit a servo device or the like connected to an actuation section of a controlled unit to exponentially carry out a follow-up actuation when a main control element of the transmitter is controlled in at least one direction about a mechanically neutral point of the main control element or cause the amount of actuation of the servo system about the mechanically neutral point to be in the form of two straight lines different in inclination with respect to the amount of control of the main control element.
2. Description of the Prior Art
In general, remote control of each of controlled units including various models such as a model car, a model airplane and the like and a variety of industrial equipments is carried out using a radio control system. Such a radio control system generally includes a transmitter for transmitting a radio wave depending on the amount of control of a plurality of control elements controlled by a manipulator, a receiver for receiving the radio wave output from the transmitter and an actuation section such as a servo device or the like for controlling a controlled unit depending on an input signal from the receiver.
FIGS. 3A and 3B are a plan view and a rear view showing a transmitter of such a conventional radio control system, the transmitter being adapted to control a model car.
A transmitter generally designated at reference numeral 1 in FIGS. 3A and 3B includes a transmitter body A in which a circuit board for transmission is arranged and a grip section B through which a manipulator holds the transmitter. More particularly, the transmitter body A includes a wheel 2 acting as one of main control elements, which is formed into a cylindrical shape. The wheel 2 is arranged so as to be rotatable in clockwise and counterclockwise directions about its central axis and normally held at its neutral point. Rotation of the wheel 2 in the clockwise or counterclockwise direction causes a steering of a model car which is a controlled unit to be controlled through the receiver and actuation section. The transmitter also includes an antenna 4 arranged on the transmitter body A for discharging an output signal in the form of a radio wave and an auxiliary control element 5 which is constituted by volumes 5a and 5b and adapted to select control characteristics of the main control elements such as the wheel 2, a trigger lever 3 described hereinafter and the like to improve controllability of the controlled unit.
The grip B includes a trigger lever 3 arranged so as to be pivotally movable about a predetermined position and serve as one of the main control elements. Direct control of the trigger lever 3 for pivotally moving it in the clockwise direction causes the amount of actuation of the servo device or the like to be increased, whereas operation of a return lever 3a formed integral with the trigger lever 3 for pivotally moving it in the clockwise direction leads to a decrease in the amount of actuation of the servo device. Thus, operation of the trigger lever 3 and return lever 3a causes a speed of a model car which is the controlled unit, its forward movement and its backward movement to be controlled. The grip section B also includes a neutral-point changeover element 6, which is adapted to change over a mechanically neutral point of the trigger lever 3 (a position at which the trigger lever 3 is mechanically held when it is not operated) in several stages, for example, three stages through a link mechanism or the like (not shown) when it is rotated. Thus, the mechanically neutral point of the trigger lever 3 is moved with respect to the total amount of control of the trigger lever 3, so that, for example, the amount of control of the trigger lever 3 is increased when its control in one direction is mainly desired, resulting in accomplishing its finer control.
On a rear surface of the transmitter body A, as shown in FIG. 3(b), a changeover switch 5c, volumes, switches and the like are arranged.
The auxiliary control element 5, as described above, is adapted to vary control characteristics of the main control element such as the wheel 2, the trigger lever 3 or the like, to thereby improve control characteristics of the controlled unit. A variation in control characteristics of the main control element may be carried out, for example, by means of a reverse mechanism which is adapted to reverse actuation of the servo device or the like loaded on the controlled unit with respect to a control direction of the wheel 2 or trigger lever 3. Alternatively, it may be attained using a mechanism which is adapted to vary the amount of actuation of the servo device about the mechanically neutral point of the wheel 2 or trigger lever 3 depending on its control direction with respect to the amount of control of the wheel 2 or trigger lever 3. In addition, a mechanism may be employed which is constructed so as to control the auxiliary element 5 with respect to the amount of control of the main control element such as the wheel 2, trigger lever 3 or the like in a manner to decrease the amount of actuation of the the servo device near the mechanically neutral point and rapidly exponentially increase it with an increase in the amount of control of the main control element, resulting in the amount of actuation of the servo device obtained at the maximum amount of control of the main control element being similar to that obtained when the auxiliary control element is not controlled (or when actuation characteristics of the servo device are not varied), as shown in FIGS. 4 and 5(a) to 5(c).
FIG. 4 illustrates an example that relationships between the amount of control of the wheel 2 and the amount of actuation of the servo device are varied depending on control of the auxiliary control element 5. More particularly, the relationships are normally linear as indicated at broken lines. However, operation of the volume 5a arranged on the transmitter body A causes the relationships to take an exponential form about the mechanically neutral point of the wheel 2 as indicated at a solid line. In other words, the auxiliary element 5 functions in a manner to cause the amount of actuation of the servo device with respect to the amount of control of the wheel 2 to be decreased near the mechanically neutral point of the wheel 2 and rapidly increased as the amount of control of the main control element approaches its maximum value (its maximum control value in each rotation direction thereof), resulting in the amount of actuation of the servo device obtained at the maximum amount of control of the wheel being similar to that obtained when the volume is not operated. This causes the amount of actuation of a steering of the controlled unit or model car to be decreased near the mechanically neutral point of the wheel 2, resulting in the controlled unit exhibiting excellent controllability such as an improvement in straight advance during its high speed traveling or on a slippery road, the desired maximum amount of actuation of the steering, elimination of effects on cornering and the like.
FIGS. 5(a) to 5(c) show relationships between the amount of control of the trigger lever 3 and the amount of actuation of the servo device. The relationships are normally linear as indicated at broken lines. Operation of the volume 5b arranged on a front surface of the transmitter A and changingover of the changeover switch 5c arranged on the rear surface of the body A cause the amount of actuation of the servo device to be exponentially varied as the amount of control of the trigger lever 3 increases exceeding each of reference points determined at positions at which the amounts of control of the trigger lever 3 are 50%, 30% and 0% based on the total amount of control of the trigger lever 3, respectively. Thus, operation or control of the volume 5b of the auxiliary control element 5 causes control characteristics of the trigger lever 3 to be varied and the changeover switch 5c transfers the reference points at which actuation characteristics of the servo device start to vary with respect to control of the trigger lever 3 as compared with during non-operation of the volume 5b.
The following description will be made supposing that each of the reference points at which the actuation characteristics of the servo device (points a, b and c in FIGS. 5(a) to 5(c)) start to be varied is regarded as an electrically neutral point of the trigger lever 3 for convenience.
Further, operation of the changeover element 6 permits the mechanically neutral point of the trigger lever 3 to be changed over in three stages or among three positions at which the amounts of control of the trigger lever 3 are 50%, 30% and 0% based on the total amount of control of the trigger lever 3, respectively. Operation of the changeover switch 5c causes the electrically neutral point of the trigger lever 3 to be moved depending on each of points for the mechanically neutral point of the trigger lever 3.
More particularly, operation or changing-over of the changeover switch 5c is carried out so that when the mechanically neutral point of the trigger lever 3 is at the position of 50% based on the total amount of control thereof, the electrically neutral point of the trigger lever 3 is at the position of 50% based on the total amount of control thereof as shown in FIG. 5(a) showing the actuation characteristics of the servo device with respect to the trigger lever 3. Likewise, when the mechanically neutral point of the trigger lever 3 is at the positions of 30% and 0% based on the total amount of its control, the electrically neutral point of the trigger lever 3 is changed over to the positions of 30% and 0% by the changeover switch 5c, respectively.
When the trigger lever 3 is controlled in a direction of increasing the amount of control of the trigger lever 3 from its mechanically neutral point, the amount of actuation of the servo device with respect to the amount of control of the trigger lever 3 is decreased near the neutral point; whereas as the amount of control of the trigger lever 3 is increased, the amount of actuation of the servo device is exponentially increased, resulting in the desired amount of actuation of the servo device being obtained at the maximum amount of control of the trigger lever 3.
For example, when a speed of the controlled unit or model car is to be controlled by the trigger lever 3, such construction not only causes the speed to be slowly increased with respect to control of the trigger lever 3, resulting in a desired maximum speed of the model car, supposing that the speed is set to be zero at the neutral point of the trigger lever 3 and a direction of increasing the amount of control of the trigger lever 3 is set to be a forward direction, but effectively prevents the model car from slipping on a slippery road, so that controllability of the model car may be highly improved. Also, setting of the mechanically neutral point of the trigger lever 3 when it is mainly desired to control the controlled unit in one direction as in a model car of which only forward movement is mainly desired, setting of the mechanically neutral point of the trigger lever 3 at the position of 30% or 0% based on the total amount of its control permits the controlled unit to be more finely controlled.
The conventional transmitter described above with reference to FIGS. 3(a) and 3(b) is so constructed that the mechanically neutral point of the trigger lever 3 is selectively changed over in one of the three stages or to one of the three positions by switching or operating the changeover element 6. Also, changing-over of the changeover switch 5c arranged on the rear surface of the transmitter body A causes the electrically neutral point of the trigger lever 3 to be changed over depending on the mechanically neutral point of the trigger lever 3.
Thus, in the conventional transmitter, it is required that the mechanically neutral point of the trigger lever 3 is changed over by the changeover element 6, whereas its electrically neutral point is changed over by the changeover switch 5c. This results in the changeover operation of the transmitter 1 being highly troublesome as well as the changeover switch 5c being often changed over to an incorrect position with respect to the mechanically neutral point of the trigger lever 3.
Changing-over of the changeover switch 5c to an incorrect position fails to cause the amount of actuation of the servo device to reach a predetermined level, when the electrically neutral point of the trigger lever 3, as shown in FIGS. 5(b) or 5(c), is at the position of 30% or 0% based on the total amount of control of the trigger lever 3 in the case that the mechanically neutral point of the trigger lever 3 is at the position of 50% based on the total amount of its control. This results in the amount of actuation of the servo device being suddenly decreased when the volume 5b of the auxiliary control element 5 is actuated to change over actuation characteristics of the servo device, to thereby lead to reckless driving or malfunction of the controlled unit or model car. Also, there is a case that the amount of actuation of the servo device at the mechanically neutral point of the trigger lever 3 is not varied depending on the positions for the neutral point of the trigger lever 3, even when the changeover switch 5c is changed over to an incorrect position. However, the trigger lever 3 fails to exhibit desired control characteristics because the actuation of the servo device with respect to the amount of control of the trigger level 3 is varied. Such a problem likewise occurs also when the relationships between the amount of control of the trigger lever 3 and the amount of actuation of the servo device about the mechanically neutral point of the trigger lever 3 are indicated at two straight lines different in inclination from each other, in the case that the electrically neutral point is incorrectly set with respect to the mechanically neutral point of the trigger lever 3.